Recently, transmission/reception of an IP-based broadcast signal has been expanded in a digital broadcasting system. In particular, in a mobile digital broadcasting such as DVB-NGH among European broadcasting standard or ATSC-MH among North American broadcasting standard, the importance of transmission/reception environment of the IP-based broadcast signal is emphasized. And, it is expected that a broadcasting system providing a service in a manner of interworking a broadcast network and the internet with each other, i.e., a hybrid broadcasting system, will be constructed in a next generation broadcasting system.
It is necessary for the next generation broadcasting system to process broadcast signals of various protocols transmitted from a plurality of sources or data. In this process, transmission of broadcast signal or data may be overloaded. Hence, it is necessary to have a method of reducing overhead of transmitted broadcast signal or data.